An efficient catalytic method for fulvene synthesis
作者:Necdet Coşkun、Ihsan Erden
DOI:10.1016/j.tet.2011.09.036
日期:2011.11
added water and solvent on the condensation of carbonyl compounds with cyclopentadiene in the presence of secondary amines were investigated. Based on these studies, a new efficient and green synthesis of fulvenes was developed.
Rapid synthesis of fulvenes is achieved using pyrrolidinium/pyrrolidine buffers in anhydrous acetonitrile. Time-dependent UV–vis absorption and NMR spectroscopy reveal that the rate and yield of fulvene formation depend strongly on both the presence of acid in the medium and the choice of solvent, and they are negatively affected by water. Kinetic data have been collected for various substrates, and
new facet of nucleophilic fulvene epoxidations has been uncovered. 6-Arylfulvenes containing an ortho or para hydroxyl group react with basic hydrogen peroxide in an unusual manner; the epoxidation of the fulvene exocyclic double bond is followed by a phenoxide ion initiated epoxide ring opening to form an o-quinone methide (o-QM) intermediate. The resulting cyclopentadienolate undergoes an unusual oxy-anion